Q: I developed an online version of my course. What is the best way to provide copyright protection at the time when students sell notes to commercial notetaking services?

A: Some faculty include a statement to the syllabus forbidding selling/buying class notes, exercises, quizzes, exams without their written permission. There are no tools to monitor the infringement of copyright when students sell notes to commercial notetaking services (FlashNote/Noteutopia/Notehall, Course Hero etc.).
Copyright protection for online course materials is a grey area. Is it legal or ethical?
There are "legal issues and the general controversy around selling class notes. Notehall and competing platform Course Hero even received a cease and desist letter from the UCSC general counsel, and it also alerted faculty members and undergraduates that the commercialization of class notes is illegal in California."